Packaging Management in Odoo 19:
UoM Conversions, Inner Packs & Pallet Configuration

from odoo import models, fields, api


class ProductPackaging(models.Model):
    _inherit = 'product.packaging'

    # ── Extended Packaging Fields ──
    packaging_tier = fields.Selection(
        selection=[
            ('each', 'Each / Unit'),
            ('inner', 'Inner Pack'),
            ('outer', 'Outer Carton'),
            ('pallet', 'Pallet'),
        ],
        string='Packaging Tier',
        default='each',
        required=True,
        help='Defines the hierarchy level in the packaging structure.',
    )
    layers_per_pallet = fields.Integer(
        string='Layers per Pallet',
        help='Number of stacked layers when this packaging is palletized.',
    )
    max_stack_weight = fields.Float(
        string='Max Stack Weight (kg)',
        help='Maximum weight before the bottom layer is crushed.',
    )
    gtin_14 = fields.Char(
        string='GTIN-14',
        size=14,
        help='GS1 identifier for this packaging level (AI 01).',
    )
    is_shipping_default = fields.Boolean(
        string='Default for Shipping',
        help='Use this packaging for carrier rate calculations.',
    )

    @api.constrains('qty')
    def _check_qty_positive(self):
        for rec in self:
            if rec.qty <= 0:
                raise models.ValidationError(
                    f"Packaging '{{rec.name}}' must have a quantity greater than zero."
                )

from odoo import models, fields, api
from odoo.exceptions import ValidationError
from odoo.tools import float_compare, float_round


class PackagingHierarchy(models.Model):
    _inherit = 'product.packaging'

    parent_packaging_id = fields.Many2one(
        'product.packaging',
        string='Parent Packaging',
        domain="[('product_id', '=', product_id), ('id', '!=', id)]",
        help='The next packaging level up (e.g., Inner Pack → Outer Carton).',
    )
    child_packaging_ids = fields.One2many(
        'product.packaging',
        'parent_packaging_id',
        string='Child Packagings',
    )
    units_per_parent = fields.Float(
        string='Units in Parent',
        compute='_compute_units_per_parent',
        store=True,
        help='How many of this packaging fit in the parent packaging.',
    )

    @api.depends('qty', 'parent_packaging_id.qty')
    def _compute_units_per_parent(self):
        for rec in self:
            if rec.parent_packaging_id and rec.qty:
                rec.units_per_parent = float_round(
                    rec.parent_packaging_id.qty / rec.qty,
                    precision_digits=2,
                )
            else:
                rec.units_per_parent = 0.0

    @api.constrains('parent_packaging_id', 'qty')
    def _check_hierarchy_divisibility(self):
        for rec in self:
            if not rec.parent_packaging_id or not rec.qty:
                continue
            parent_qty = rec.parent_packaging_id.qty
            remainder = parent_qty % rec.qty
            if float_compare(remainder, 0, precision_digits=4) != 0:
                raise ValidationError(
                    f"Parent packaging '{{rec.parent_packaging_id.name}}' "
                    f"(qty={{parent_qty}}) is not an exact multiple of "
                    f"'{{rec.name}}' (qty={{rec.qty}}). "
                    f"Remainder: {{remainder}}."
                )

from odoo import models, api
from odoo.tools import float_round


class DeliveryCarrier(models.Model):
    _inherit = 'delivery.carrier'

    def _get_packages_from_picking(self, picking):
        """Build package list with accurate dimensions for rate requests.

        Override to use packaging-level dimensions instead of
        the picking's default single-package assumption.
        """
        packages = []

        for move_line in picking.move_line_ids.filtered('qty_done'):
            product = move_line.product_id
            qty = move_line.qty_done

            # Find the shipping-default packaging
            shipping_pkg = product.packaging_ids.filtered(
                'is_shipping_default'
            )[:1]

            if not shipping_pkg or not shipping_pkg.package_type_id:
                # Fallback: single package with product weight
                packages.append({
                    'weight': product.weight * qty,
                    'length': 0,
                    'width': 0,
                    'height': 0,
                })
                continue

            pkg_type = shipping_pkg.package_type_id
            num_packages = int(qty // shipping_pkg.qty)
            remainder = qty % shipping_pkg.qty

            # Full packages
            for _ in range(num_packages):
                actual_weight = product.weight * shipping_pkg.qty
                dim_weight = float_round(
                    (pkg_type.packaging_length
                     * pkg_type.width
                     * pkg_type.height) / 5000.0,
                    precision_digits=2,
                )
                packages.append({
                    'weight': max(actual_weight, dim_weight),
                    'length': pkg_type.packaging_length,
                    'width': pkg_type.width,
                    'height': pkg_type.height,
                })

            # Remainder (partial package)
            if remainder > 0:
                packages.append({
                    'weight': product.weight * remainder,
                    'length': pkg_type.packaging_length,
                    'width': pkg_type.width,
                    'height': pkg_type.height,
                })

        return packages